1. Field of the Invention
The invention relates to a process and device for determining the thickness transverse profile and thickness longitudinal profile of a running strip of material.
2. Background Information
The are already a large number of measuring processes known in the prior art. The main objective in each case is to acquire precisely the thickness transverse profile, i.e. the measurement of the strip thickness over the width of the strip transverse to the direction of run of the strip, and the strip longitudinal profile, i.e. the measurement of the strip thickness in the centre of the strip or at other longitudinal positions lengthways to the direction of run of the strip. This objective has hitherto only been fulfilled if, during the measuring process, the band thickness is acquired simultaneously in the centre of the strip and the band thickness in the individual strip position in each case, transverse to the strip.
This is achieved, for example, by the simultaneous multi-channel profile measurement process, in which, on the one hand, in the centre of the material strip a measuring unit consisting of at least one source of radiation and at least one detector makes direct measurements of the thickness of the strip, and therefore determines the thickness longitudinal profile. On the other hand, separate measuring units are provided for, intended to determine the thickness transverse profile, which acquire the area of the edges of the material strip. Due the requirements indicated above with regard to the scale of the values to be measured and the precision of measurement required, the known devices are correspondingly elaborate and expensive. Thus, for example, at least two separate measuring units with a measuring head each are required, consisting of an arrangement of a radiation source and at least one detector, or one measuring unit with several measuring heads.
The processes and devices described in the foregoing are intended predominantly for continuous casting, for blooming trains, or for the intake of manufacturing stepped rolls. This is due to the fact that further progress in the optimisation of the rolling process of metal strips with stepped rolls can no longer be considered without a precise knowledge of the circumstances in the intake area.
The invention is therefore based on the technical problem of reducing the technical elaboration and expense of the measuring device, while still maintaining a precise determination of the thickness transverse profile and the thickness longitudinal profile of a running strip of material.
The technical problem outlined above is resolved according to the invention by a process:
a) In which, with the aid of a measuring unit, strip thicknesses D are determined in at least two measurement areas, whereby one measuring unit features at least one radiation source 8 and at least two detectors 10, whereby a measurement area 22 is the volumetric area of the material strip 2, which has been run through by the radiation, this radiation being measured by a detector 10 allocated for this purpose, and whereby the measurement areas are arranged at a distance from one another transverse to the direction of run of the strip;
b) In which the longitudinal position of the thickness longitudinal profile to be determined is determined longitudinally to the direction of run of the strip;
c) In which the band thickness Do in the longitudinal position is measured directly by the measuring unit, and the value of a correction value xcex94K is equal to zero;
d) In which the measuring unit is set transverse to the direction of run of the strip and the amount of the setting xcex94P is determined by relation to the longitudinal position;
e) In which, from the strip thicknesses D determined at the measuring areas, the gradient k of the strip thicknesses D transverse to the direction of run of the strip is calculated;
f) In which the correction value xcex94K is recalculated as the total from the previous correction value xcex94K and the product of the gradient k and the value of the setting xcex94P;
g) In which the mean strip thickness Dm is calculated from the strip thicknesses D determined in the measurement areas;
h) In which the corrected strip thickness D0k in the longitudinal position is calculated as the sum from the strip thickness Dm and the new correction value xcex94K;
i) In which the steps d) to h) are repeated within a setting cycle until the measuring unit has been set up to a maximum offset setting transverse to the longitudinal position and back again as far as a position in which the strip thickness D0 is measured directly in the longitudinal position by the measuring unit; and
j) In which the thickness transverse profile is determined from the repeatedly determined strip thicknesses Dm and the thickness longitudinal profile is determined from the repeatedly corrected strip thicknesses D0k.
The process sequence described can also be designated as a traversing multi-channel profile measurement and can be performed with one measuring unit for the objective on which the invention is based.
If, during the thickness transverse profile acquisition, the measuring unit is located outside the longitudinal position, the strip thickness is determined uniformly in the longitudinal position, since the changes in thickness which result from the thickness transverse profile are conducted additively by means of a mathematical process. In this situation, the thickness transverse profile is acquired by means of thickness differentials to the strip thickness in the longitudinal position, since the strip thickness varies in the longitudinal direction of the strip. Overall, it must be taken into account for the precision of the process that the deviations between the strip thickness in the centre of the strip and at the outer edge will lie in a range, for example, of less than 5%.
Accordingly, with the sequence of the process according to the invention, it is guaranteed that the technical elaboration of the measuring device will be reduced, while still retaining a precise determination of the thickness transverse profile and the thickness longitudinal profile of a running strip of material. Because the process according to the invention is used in particular in the intake area of a roller train, the strip running speed is so low that, with a traversing speed in the range from 5-15 m/min, a satisfactorily close-meshed measurement of the material strip can be achieved.
According to a further doctrine of the present invention, the technical problem described heretofore is resolved by a device for determining the thickness transverse profile and the thickness longitudinal profile of a running strip of material, with a housing, with at least one radiation source arranged in the housing, and with at least two detectors arranged in the housing which are arranged at a distance from one another transverse to the direction of run of the strip, and are aligned at different angles to the minimum of one radiation source, whereby the material strip is arranged between the radiation source and the detectors, and whereby the detectors assess the material strip in sections transverse to the direction of run of the strip, and that setting media for the synchronous adjustment of the radiation source and the detectors relative to the material strip.
In addition to this, the technical problem is resolved by the use of a device as described heretofore for the performance of the process described above.